1. Field of the Invention
The present invention relates to receiving devices and antennas, and can be applied to, for example, mobile phones capable of receiving digital radio broadcasting. The present invention suggests an antenna having a superior mechanical strength, a superior design, and improved performance resulting from a configuration that is more simplified than that of the related art by shielding a part of core-wire-side cables from a main-unit-side end thereof to a given point before the other end thereof with a covered wire and connecting the main-unit-side end of this covered wire to a tuner, and a receiving device employing this antenna.
2. Description of the Related Art
In the related art, various improvements are attempted regarding antennas in portable receiving devices. More specifically, such antennas are desired not to spoil a design of receiving devices, to prevent an influence on a human body, and to be more resistant to an influence of noises emitted from other devices.
Regarding the design among these desires, improvements for not spoiling the design have been made on receiving devices by including an antenna therein. However, when the reception frequency is low, the size of antennas becomes larger, which makes it difficult to include the antennas in the receiving devices. Accordingly, in the related art, when the reception frequency is low, receiving devices generally employ rod antennas. Still, the use of a rod antenna complicates a configuration of receiving devices and undesirably spoils the design thereof due to protrusion of the rod antenna.
Accordingly, various methods for using an earphone cable as an antenna have been suggested recently. However, when an earphone cable is simply used as an antenna, the earphone cable touches a human body and a position touching the human body also changes variously, which prevents the earphone cable from fully demonstrating a function as an antenna.
Accordingly, in the related art, e.g., in Japanese Unexamined Patent Application Publication No. 2005-64742, various improvements for preventing a portion of an earphone cable touching a human body from functioning as an antenna when the earphone cable is used as an antenna have been suggested.
Nevertheless, in these methods, a high-frequency blocking element for blocking high-frequency signals from flowing into a specific region has to be provided at a junction part of a portion not functioning as an antenna and a portion functioning as an antenna. This undesirably complicates a configuration of the junction part, and further deteriorates a mechanical strength at the junction part. A design is also restricted undesirably. In addition, it is difficult to completely block a flow of high-frequency signals into the specific region even if a high-frequency blocking circuit is provided at the junction part. For this reason, issues not fully solved for practical use still exist regarding the performance.